Mobile communications systems are made up of a plurality of cells. Each cell provides a radio communication center in which a mobile station establishes a call with another mobile station or a wireline unit connected to a public switched telephone network (PSTN) or a packet data network. Each cell typically includes a radio base station, with each base station connected to a mobile switching center for processing circuit-switched calls, or to a packet data serving node for processing packet-switched communications.
Various wireless protocols exist for defining communications in a wireless network. One such protocol is the time-division multiple access (TDMA) standard. According to TDMA, each radio frequency (RF) carrier carries a frame that is divided into plural time slots to increase the number of mobile stations that can be supported per RF carrier. Examples of TDMA wireless networks include IS-136 and GSM (Global System for Mobile) wireless networks.
Another type of wireless technology is provided by the code-division multiple access (CDMA) standard. CDMA is a spread spectrum wireless communications protocol in which transmission is based on the spread spectrum modulation technique to allow many users to have access to the same band of carriers.
Traditionally, wireless networks have been designed for carrying circuit-switched voice traffic. However, with the explosion of the Internet and intranets, packet-switched communications (e.g., web browsing, electronic mail, and so forth) have become common. As a result, third generation (3G) and beyond wireless technologies have been developed to transition to higher bandwidth and more efficient packet-switched communications over wireless networks.
One example of a 3G wireless technology is the CDMA 2000 technology, as defined by the IS-2000 Standard. A CDMA 2000 wireless communications system is capable of supporting both traditional voice traffic (circuit-switched voice traffic) as well as packet-switched traffic, such as web browsing, electronic mail, voice-over-IP (Internet Protocol), and so forth. Other types of 3G wireless technologies have also been implemented, such as the 1xEV-DO, 1xEV-DV, UMTS (Universal Mobile Telecommunication System), and Enhanced GPRS (General Packet Radio Service) technologies, among others.
In conventional wireless systems, control and traffic channels are defined for carrying control and traffic data, respectively. To establish a call, control signaling is initially exchanged between a mobile station and a base station. For example, in a CDMA wireless network, a mobile station can originate a call by sending an origination message on an access channel to a base station. The base station in turn assigns various network resources to the mobile station by sending an assignment message to the mobile station over a paging channel. For a mobile station-terminated call (in which the call is originated by another endpoint and targeted to the mobile station), the base station pages the mobile station on the paging channel.
Typically, certain control channels, such as the paging channel, are communicated at a fixed power level. The fixed power level of the paging channel is selected to achieve a compromise between reliability of communication of control messages and available bandwidth or capacity within a given cell. The higher the power level of the paging channel, the lower the bandwidth or capacity available in a given cell. On the other hand, reducing the power level of a paging channel increases the likelihood of errors occurring in the communication of control messages between the base station and the mobile station, which reduces reliability of wireless communications.
Therefore, in conventional wireless communications networks, because the paging channel is transmitted at a fixed power level, performance within a cell may not be optimized.